The present invention relates generally to methods and apparatus for completing wells, such as oil and gas wells, and more specifically relates to methods and apparatus for completing multiple intervals in such wells. Methods and apparatus in accordance with the present invention are useful in most wells having multiple intervals requiring completion, but are believed to be of extreme benefit in highly deviated, or in so-called "horizontal", wells wherein multiple intervals will be completed in a single potential producing formation or "zone".
Currently, highly deviated or horizontal wells are typically completed by individually completing multiple individual intervals within the zone of interest along the length of the well. Conventional techniques for performing such completions typically include the perforating of the lowest interval in the well; the treating of that interval (such as by acidizing, fracturing, etc.), if necessary; and the subsequent killing of the interval to allow a repeat of the above sequence on the next highest interval in the well. In a common situation where tubing conveyed perforating guns are utilized to perforate the well, separate tubing conveyed perforating gun assemblies are typically run into the hole for perforating each interval. Such operations are not only extremely time consuming, requiring multiple trips of the tubing in and out of the well, but also often involve the killing of the lower perforated intervals by pumping fluid into the intervals, with potentially deleterious effects upon formation productivity.
Accordingly, the present invention provides a new method and apparatus whereby multiple intervals in a well may be perforated essentially simultaneously, and whereby each interval may be selectively either shut-in or isolated for treatment, eliminating the need to kill a perforated interval. Additionally, the present invention provides a new method and apparatus whereby multiple zones within a well may be completed with a minimal number of trips of tubing in and out of the borehole, and whereby snubbing tubing or coiled tubing may be used for many of these trips, thereby simplifying the equipment for the operation, and allowing the operation to be performed in an optimally short period of time.